Glycosylation-independent binding to extracellular domains 11-13 of mannose-6-phosphate/insulin-like growth factor-2 receptor mediates the effects of soluble CREG on the phenotypic proliferation of vascular smooth muscle cells

Background The present study aimed to investigate the detailed mode and specific sites for their binding as well as the functional relevance of this binding in the phenotypic proliferation of vascular smooth muscle cells(SMCs). Methods CREG knocked-down SMCs were employed to evaluate the biological activity of wtCREG and mCREG.Expressions of SMC differentiation markers SM myosin heavy chain(SM-MHC),SM-actin,heavy caldesmon and myocardin were determined by Western blotting using specific antibodies. Cellular growth of SMCs was assessed by bromide dewuridine (BrdU) incorporation and cell cycle analysis on fluorescence-activated cell sorting(FACS).A solid-phase binding assay was used to study the binding of CREG to extracellular domains of M6P/IGF2R.The cellular co-localization of the two recombinant CREGs with M6P/IGF2R was detected on SMC surface by immunoprecipitation and immunofluorescence analysis.Results The molecular weight of wtCREG was around 30 kD while that of the mCREG was～25 kD.Treatment of wtCREG with PNGase F reduced its molecular weight from～30 kD to～25 kD,whereas PNGase F treatment had no effect on the molecular weight of mCREG.Both wtCREG and mCREG proteins enhanced SMC differentiation,inhibited BrdU incorporation,and arrested cell cycle progression when added to the culture medium.In CREG knocked-down SMCs,the amount of CREG detected by immunoblotting in M6P/IGF2R immunoprecipitates was significantly reduced when compared to normal cells.Both recombinant CREGs co-immunoprecipitated with M6P/IGF2R, although slightly reduced amount of the mutant CREG was detected in M6P/IGF2R immunoprecipitates.Immunostaining revealed that His-tagged CREGs co-localized with IGF2R on the cell surface in a glycosylation-independent manner.In vitro binding assay showed that CREGs bound to M6P/ IGF2R extracellular domains 7-10 and 11-13 in a glycosylation -dependent and -independent manner,respectively.Further blocking experiments using soluble M6P/IGF2R fragments and M6P/IGF2R neutralizing antibody indicated that the biological activities of recombinant CREGs in SMC growth and the up-regulation of SMC differentiation markers were all abolished by treatment with the M6P/IGF2R neutralizing antibody. However,although the growth inhibitory effect of wtCREG was nearly abolished by D7-10 or D11-13,the effect of mCREG was only reversed by Dll-13,indicating that the binding to domains 11-13 is required for CREG to modulate the proliferation of SMCs.Conclusions These data suggest that solubleCREG proteins can exert their biological function via binding to the extracellular domains 7-10 and 11-13 of cell surface M6P/IGF2R in both a glycosylation-dependent and -independent manner.

Characterization of recombinant humanized collagen type III and its influence on cell behavior and phenotype

Collagen made a tremendous impact in the field of regenerative medicine as a bioactive material.For decades,collagen has been used not only as a scaffolding material but also as an active component in regulating cells’biological behavior and phenotype.However,animal-derived collagen as a major source suffered from problems of immunogenicity,risk of viral infection,and the unclear relationship between bioactive sequence and function.Recombinant humanized collagen(rhCol)provided alternatives for regenerative medicine with more controllable risks.However,the characterization of rhCol and the interaction between rhCol and cells still need further investigation,including cell behavior and phenotype.The current study preliminarily demonstrated that recombinant humanized collagen type III(rhCol III)conformed to the theoretical amino acid sequence and had an advanced structure resembling bovine collagen.Furthermore,rhCol III could facilitate basal biological behaviors of human skin fibroblasts,such as adhesion,proliferation and migration.rhCol III was beneficial for some extracellular matrix-expressing cell phenotypes.The study would shed light on the mechanism research of rhCol and cell interactions and further understanding of effectiveness in tissue regeneration.

Depletion but Activation of CD56dimCD16+ NK Cells in Acute Infection with Severe Fever with Thrombocytopenia Syndrome Virus

Severe fever with thrombocytopenia syndrome(SFTS)is an emerging infectious disease with high mortality(12%–30%).The mechanism by which the SFTS bunyavirus(SFTSV)causes severe illness remains unclear.To evaluate the phenotypic and functional characteristics of the NK cell subsets in SFTS patients,twenty-nine SFTS patients were sequentially sampled from admission until recovery.Phenotypic and functional characteristics of NK cell subsets in circulating blood were analysed via flow cytometry.Then,correlations between NK cell subset frequencies and the SFTS index(SFTSI)were evaluated in all SFTS patients(15 mild,14 severe)upon admission.The frequencies of CD56dimCD16+NK cells were greatly decreased in early SFTSV infection and were negatively correlated with disease severity.Additionally,higher Ki-67 and granzyme B expression and relatively lower NKG2 A expression in CD56dimCD16+NK cells were observed in acute infection.Moreover,the effector function of CD56dimNK cells was increased in the acute phase compared with the recovery phase in nine severe SFTS patients.Additionally,interleukin(IL)-15,interferon(IFN)-a,IL-18 and IFN-c secretion was markedly increased during early infection.Collectively,despite depletion of CD56dimCD16+NK cells,activation and functional enhancement of CD56dimCD16+NK cells were still observed,suggesting their involvement in defence against early SFTSV infection.

Functional annotation map of natural compounds in traditional Chinese medicines library: TCMs with myocardial protection as a case

The chemical complexity of traditional Chinese medicines(TCMs) makes the active and functional annotation of natural compounds challenging. Herein, we developed the TCMs-Compounds Functional Annotation platform(TCMs-CFA) for large-scale predicting active compounds with potential mechanisms from TCM complex system, without isolating and activity testing every single compound one by one. The platform was established based on the integration of TCMs knowledge base, chemome profiling, and high-content imaging. It mainly included:(1) selection of herbal drugs of target based on TCMs knowledge base;(2) chemome profiling of TCMs extract library by LC-MS;(3) cytological profiling of TCMs extract library by high-content cell-based imaging;(4) active compounds discovery by combining each mass signal and multi-parametric cell phenotypes;(5) construction of functional annotation map for predicting the potential mechanisms of lead compounds. In this stud TCMs with myocardial protection were applied as a case study, and validated for the feasibility and utility of the platform. Seven frequently used herbal drugs(Ginseng, etc.) were screened from 100,000 TCMs formulas for myocardial protection and subsequently prepared as a library of 700 extracts. By using TCMs-CFA platform, 81 lead compounds, including 10 novel bioactive ones, were quickly identified by correlating 8089mass signals with 170,100 cytological parameters from an extract library. The TCMs-CFA platform described a new evidence-led tool for the rapid discovery process by data mining strategies, which is valuable for novel lead compounds from TCMs. All computations are done through Python and are publicly available on GitHub.